- TextBox is a superset of Paragraph, so Paragraph is deprecated
- adds support for a cursor, which can be moved
- the `Text` field is now private, replaced with `SetText`, `InsertText`, and `ClearText` methods
TODO:
- adding focusable widgets support to termui might clean up the API since we could potentially move the event handling from client side to library side
- add support for scrolling the TextBox view
- fix the cursor position on linewrap
- fix linewrapping
- add line number support
